(a) Field of the Invention
The present invention relates generally to deployable structures, and specifically to systems for deploying satellite appendages such as reflectors for satellite antennae.
(b) Description of Related Art
Deployment systems for satellite appendages such as umbrella-type reflectors typically include a screw mechanism or a rack-and-pinion drive. Screw mechanisms employ a motor to rotate a metallic lead screw which rotation in turn drives a nut along the major axis of the lead screw. The nut is operatively connected to one or more structural members of the appendage such that movement of the nut causes the appendage to deploy.
Rack-and-pinion drives typically employ a motor to drive a pinion which in turn engages and moves a rack which meshes with the pinion. The rack is operatively connected to one or more structural members of the appendage such that movement of the rack causes the appendage to deploy.
Such screw mechanisms and rack-and-pinion drives have a number of disadvantages. There is potential for the screw mechanism or rack-and-pinion drive to jam, experience problems due to thermal expansion/contraction, or to exhibit unacceptable wear in use, resulting in improper deployment or a complete failure to deploy the appendage. Such potential problems make such mechanisms less reliable than might otherwise be desired.
Also, typical satellite appendages require a launch lock apparatus that relies on pyro-technic release devices. Such pyro-technic devices present safety and reliability problems and require additional electronics for the control and actuation thereof. Pyro-technic devices also require extensive design and testing efforts to ensure that the appendage structure can withstand loads associated with "pyro shock" and the resulting dynamic deployment motion which is difficult to analyze and/or simulate in a 1-G deployment environment (i.e. in a ground-based test). Pyrotechnics also require refurbishment after each use.
Accordingly, there is a need for a deployment system for satellite appendages that is configured so as to minimize or eliminate the aforementioned problems.